1. Field of the Invention
The present invention relates to a wireless data transmitting and receiving system that detects a torque and/or a rotation angle from a torque sensor and/or a rotation angle sensor disposed in a rotary shaft of a tightening machine to tight a bolt, a nut, a screw or the like, and wirelessly transmits the same to a data receiving unit.
2. Description of the Related Art
In a tightening machine that performs tightening by a torque method, a tightening torque is controlled by detecting a load of a power machine, that is, a current value of the power machine and using the current value as an index. In this method of detecting the current value to control the tightening torque, if the current value varies due to the variation of a voltage or the like, an accurate tightening torque cannot be obtained. Furthermore, since force is transmitted to a rotary shaft from the power machine through a deceleration mechanism, the tightening torque is affected by a transmission efficiency of the deceleration mechanism. That is, when the tightening machine continues to be used with a tightening torque to a current value of a new tightening machine, conformability is generated in the deceleration mechanism, which increases the transmission efficiency of the deceleration mechanism, resulting in too high a tightening torque to the same current value. Accordingly, for confirming the actual tightening torque, additional work of measuring an increasingly tightening torque by a wrench after tightening or the like is necessary.
In order to solve this problem, there is proposed a tightening machine of a bolt, a nut, a screw and the like that is equipped with a tightening-torque measuring unit to detect and display a tightening torque (e.g., refer to Japanese Patent Application Laid-Open No. 2006-21272).
In the tightening machine of Patent Literature 1, the tightening-torque measuring unit has a torque sensor such as a strain gauge, and display means electrically connected to the torque sensor, and the tightening-torque measuring unit is directly attached to a rotary shaft of the tightening machine so that the tightening torque can be detected and displayed.
In the tightening machine of Patent Literature 1, the rotary shaft to which the tightening-torque measuring unit is attached is made up of an inner shaft and an outer shaft that can rotate in a reverse direction to each other, and has a reaction force receiver at an outer shaft terminal end. The tightening-torque measuring unit is disposed in the outer shaft to which the reaction force receiver is attached. That is, since the tightening-torque measuring unit rotates integrally with the outer shaft, the display means cannot be sufficiently checked visually during rotation of the outer shaft or at some rotation stop positions of the outer shaft.
Moreover, in the case where the rotary shaft is put in the recessed portion in tightening a bolt or the like in a recessed portion or the like, the tightening-torque measuring unit is in the recessed portion, which may disable the tightening torque to be visually checked.
That is, in the tightening machine of Patent Literature 1, since the tightening-torque measuring unit is attached to the outer shaft side of the rotary shaft, and the display means is provided in the tightening-torque measuring unit, during the tightening, the tightening-torque measuring unit may move to a position where visual check is disabled, or at some rotation stop positions of the outer shaft, the display means cannot be visually checked. Moreover, the tightening-torque measuring unit is attached to the outer shaft side, and thus, when the actual tightening is performed by the inner shaft and the reaction force is received by the outer shaft, a difference between a torque acting on the outer shaft and a torque acting on the inner shaft actually performing the tightening may be caused.
Furthermore, in the tightening machine of Patent Literature 1, in order to display a torque value detected by the tightening-torque measuring unit on a display provided on the tightening machine body side, the tightening-torque measuring unit and the display need to be connected by a signal line (wired). However, since the tightening-torque measuring unit rotates together with the rotary shaft, the signal line may wind around the tightening-torque measuring unit, or may jam during working, which causes a possibility of disconnection. Moreover, since in the signal line, electric noise is easily carried, it can be considered that the accurate torque value is not sent. Although an electric-signal transmitting mechanism by a collector ring or the like can also be considered, the tightening-torque measuring unit itself is increased in size, leading to a deterioration of workability.
Moreover, in a tightening machine that performs tightening by a rotation-angle control method, an encoder is attached to a rotary shaft of a power machine, or a slit plate and a photo interrupter are attached to the rotary shaft to detect the number of rotations of the power machine, and a rotation angle of the rotary shaft is controlled with a count of the number of rotations used as an index. In this case as well, since the rotation is transmitted to the rotary shaft through a deceleration mechanism from the power machine, the control is affected by elastic deformation of the deceleration mechanism and the like.
Accordingly, although the actual rotation angle of a nut after tightening can be visually confirmed roughly, additional work by an angle gauge or the like after tightening is necessary for confirming the accurate tightening angle.
Furthermore, in a tightening machine that performs tightening by a torque gradient method, a gradient of a torque to a rotation angle of a nut is detected to perform control with variation of a value thereof used as an index.
However, in the current tightening machine that performs the tightening by the torque gradient method, since for the torque, a current value of the power machine is used as an index and for the rotation angle, a tightening time is used as an index, a gradient of the current value of the power machine to the tightening time is detected instead of the gradient of the torque to the rotation angle of the nut so as to perform the control with the variation of the value used as the index, thereby resulting in fluctuation of accuracy. Moreover, the tightening confirmation is performed by actually tightening several bolts and graphing the current value of the power machine to the tightening time at each point, and thus, devices to detect the tightening time and the current time thus need to be connected to the tightening machine.
Furthermore, in the current tightening machine, in the case where with a predetermined torque set for the tightening machine, a bolt already tightened is to be further tightened, if the torque of the bolt is less than the predetermined torque, the bolt is rotated to be tightened with the predetermined torque. However, even in the case where the bolt has already been tightened with a torque larger than the predetermined torque, when the rotary shaft of the tightening machine reaches the predetermined torque, the tightening is finished even if the bolt is not rotated, and it is determined that the bolt has been tightened with the predetermined torque.
An object of the present invention is to provide a wireless data transmitting and receiving system capable of wirelessly transmitting a signal regarding a torque acting on a rotary shaft and/or a rotation angle of the rotary shaft from a data transmitting unit disposed in the rotary shaft to a data receiving unit.